winscp512automation dll can be used with winscp 5.1.1?

Hi There,
I am currently having winscp 5.1.1 installed and can I use the
winscp512 automation dll with winscp 5.1.1 or where can I find
winscp511 automation dll?
Note:
Since we installed winscp 5.1.1 version in all our Dev/System/UAT/PROD servers
we cannot install new version of winscp512

Regards,
S.Sasidharan

You can download all older version here:
https://sourceforge.net/projects/winscp/files/

Thought, I strongly discourage you from using the old vesions.